The use of radio frequency identification (RFID) tags is well known. RFID tags are commonly used in a wide variety of fields such as security-locks for automobiles, to control access to buildings, other security applications, to track and manage inventory, and to provide identification to tagged items.
Typical RFID tags have a microprocessor electrically connected to an antenna. When used to track or manage inventory, the microprocessor stores unique identifying data associated with the inventory. An operator can use an external receiver/reader to retrieve the stored data and process the inventory.
Recently, the demand for RFID tags has increased as companies explore alternative business processes to maintain and/or increase profitability. Traditionally, companies have attempted to predict the sales volume of a particular item at a store and then ship a set number or amount of goods to the store based on the sales volume prediction. This business process has the potential to reduce company profitability, as the sales volume prediction may over estimate the demand, resulting in the store having to inventory and maintain the item for a longer time period than desired. A store may even be forced to mark down the price of an item once the item's saleable life is nearing an end or, in the case of food, expiration is near or been reached (e.g. perishable goods, seasonal items, fashion trends, etc.). Alternatively, the sales volume prediction may underestimate the demand, thereby reducing company sales and impacting profitability as consumers are forced to shop elsewhere to purchase an out of stock product.
RFID tags have the potential to increase company profitability by allowing the company to continuously monitor the supply of a product at a store. Using RFID tags allows a company to quickly respond to low store inventory without having to take physical inventory counts to ensure an adequate supply of goods while avoiding the risks associated overstocking a product. Additionally, a company can monitor the sales rate of a product at a store, which can help the company predict future sales trends so that the company can make alterations within the supply chain as necessary to maintain an appropriate supply and ready availability of goods.
The increased demand for RFID tags has created a need for a manufacturing method that can quickly and efficiently produce RFID tag antennas. One such method is disclosed in U.S. Patent Application No. 2007/0171129 A1. This method includes the steps of, first, providing a reinforced metal foil laminate which includes a foil bonded to a reinforcement layer, and a carrier layer bonded to the metal foil laminate. The method then includes the step of using a rotary die cutter to cut an antenna pattern through the metal foil laminated to the carrier layer. The method concludes with the step of removing an undesired matrix portion of the reinforced metal foil laminate to provide a metal foil laminate antenna disposed on the carrier layer. An RFID tag 5 created by this method is shown in FIG. 1.
Publications, patents and patent applications are referred to throughout this disclosure. All references cited herein are hereby incorporated by reference.
With reference to FIG. 1, the RFID tag 5 has an antenna structure 10 formed out of a reinforced conductive layer. The antenna structure has a generally T-shaped opening 15 that defines a first antenna contact end 20 and a second antenna contact end 25 spaced apart from one another by a gap 30. A first contact extension 35 and a second contact extension 40 substantially extend from the first antenna contact end 20 and the second contact end 25, respectively, toward the gap and allow a microprocessor 45 to be electrically coupled to the antenna structure 5. It should be understood that any shape may be suitable for the antenna opening and the reference to a “T” shaped opening is used for exemplary illustrative purposes only.
A rotary die cutter to cut an RFID antenna pattern is advantageous because rotary die cutting is both fast and inexpensive. However, rotary die cutters have poor resolution, and are limited to having a minimum distance between cut lines of 1 mm. Accordingly, the gap 30 of the RFID tag 1 in FIG. 1 creates, at a minimum, a 1 mm void between the first contact antenna end 20 and the second contact antenna end 25. This distance is too great for the microprocessor chip 45 to bridge. As such, the chip 45 cannot be directly coupled to the antenna structure 10. Rather, the first contact extension 35 and the second contact extension 40 must be used to substantially bridge the gap 30 before the chip 45 can be electrically coupled to the antenna structure 10.
An additional problem with using a rotary die cutter to cut a RFID antenna pattern is that the cylindrical die used by the rotary die cutter cannot be quickly or easily changed. Accordingly, the antenna design is not readily changeable, and thus it is often not economically feasible to produce small batches of a particular antenna design due to the constant need to change out die heads. Furthermore, any change in an antenna design would require a large lead-time, as a new cylindrical die must be manufactured each time the antenna design is changed. This can create a large inventory of die heads. The storage of which can occupy valuable factory floor space.
What is needed is an improved method of manufacturing RFID tags that eliminates the respective disadvantages of prior process.